Method and apparatus for user equipment directed radio resource control in a umts network

ABSTRACT

A method and apparatus for improved battery performance of user equipment in a wireless network having multiple radio resource control (RRC) states, the method comprising the steps of: monitoring, at the user equipment, application data exchange; determining when no application on the user equipment is expected to exchange data; and initiating, from the user equipment, a transition to a less battery demanding radio resource control state or mode.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/302,263, filed Dec. 14, 2005, the content of which is incorporatedherein by reference.

FIELD OF THE APPLICATION

The present application relates to radio resource control between UserEquipment (UE) and Universal Terrestrial Radio Access Network (UTRAN),and in particular to the transitioning between modes and states in aUMTS network.

BACKGROUND

A Universal Mobile Telecommunication System (UMTS) is a broadband,packet based system for the transmission of text, digitized voice, videoand multi-media. It is a highly subscribed to standard for thirdgeneration and is generally based on Wideband Coded Division MultipleAccess (W-CDMA).

In a UMTS network, a Radio Resource Control (RRC) part of the protocolstack is responsible for the assignment, configuration and release ofradio resources between the UE and the UTRAN. This RRC protocol isdescribed in detail in the 3GPP TS 25.331 specifications. Two basicmodes that the UE can be in are defined as “idle mode” and “UTRAconnected mode”. UTRA stands for UMTS Terrestrial Radio Access. In idlemode, the UE is required to request a RRC connection whenever it wantsto send any user data or in response to a page whenever the UTRAN or theServing GPRS Support Node (SGSN) pages it to receive data from anexternal data network such as a push server. Idle and Connected modebehaviors are described in details in 3GPP specifications TS 25.304 andTS 25.331.

When in a UTRA RRC connected mode, the device can be in one of fourstates. These are:

-   -   CELL-DCH: A dedicated channel is allocated to the UE in uplink        and downlink in this state to exchange data. The UE must perform        actions as outlined in 3GPP 25.331.    -   CELL_FACH: no dedicated channel is allocated to the user        equipment in this state. Instead, common channels are used to        exchange a small amount of bursty data. The UE must perform        actions as outlined in 3GPP 25.331 which includes the cell        selection process as defined in 3GPP TS 25.304.    -   CELL_PCH: the UE uses Discontinuous Reception (DRX) to monitor        broadcast messages and pages via a Paging Indicator Channel        (PICH). No uplink activity is possible. The UE must perform        actions as outlined in 3GPP 25.331 which includes the cell        selection process as defined in 3GPP TS 25.304. The UE must        perform the CELL UPDATE procedure after cell reselection.    -   URA_PCH: the UE uses Discontinuous Reception (DRX) to monitor        broadcast messages and pages via a Paging Indicator Channel        (PICH). No uplink activity is possible. The UE must perform        actions as outlined in 3GPP 25.331 including the cell selection        process as defined in 3GPP TS 25.304. This state is similar to        CELL_PCH, except that URA UPDATE procedure is only triggered via        UTRAN Registration Area (URA) reselection.

The transition from an idle to the connected mode and vise-versa iscontrolled by the UTRAN. When an idle mode UE requests an RRCconnection, the network decides whether to move the UE to the CELL_DCHor CELL_FACH state. When the UE is in an RRC connected mode, again it isthe network that decides when to release the RRC connection. The networkmay also move the UE from one RRC state to another prior to releasingthe connection. The state transitions are typically triggered by dataactivity or inactivity between the UE and network. Since the network maynot know when the UE has completed data exchange, it typically keeps theRRC connection for some time in anticipation of more data to/from theUE. This is typically done to reduce the latency of call set-up andradio bearer setup. The RRC connection release message can only be sentby the UTRAN. This message releases the signal link connection and allradio bearers between the UE and the UTRAN.

The problem with the above is that even if an application on the UE hascompleted it data transaction and is not expecting to any further dataexchange, it still waits for the network to move it to the correctstate. The network may not be even aware of the fact that theapplication on the UE has completed its data exchange. For example, anapplication on the UE may use its own acknowledgement-based protocol toexchange data with its application server which is connected to the UMTScore network. Examples are applications that run over UDP/IPimplementing their own guaranteed delivery. In such a case, the UE knowswhether the application server has sent or received all the data packetsor not and is in a better position to determine if any further dataexchange is to take place and hence decide when to terminate the RRCconnection. Since the UTRAN controls when the RRC connected state ischanged to a different, less battery intensive state or into an idlemode, and the fact that UTRAN is not aware of the status of datadelivery between the UE and external server, the UE is forced to stay ina higher data rate and intensive battery state than the required stateor mode, thereby draining battery life and wasting network resources.

BRIEF DESCRIPTION OF THE DRAWINGS

The present application will be better understood with reference to thedrawings in which:

FIG. 1 is a block diagram showing RRC states and transitions;

FIG. 2 is a schematic of a UMTS network showing various UMTS cells and aURA;

FIG. 3 is a block diagram showing the various stages in an RRCconnection setup;

FIG. 4A is a block diagram of an exemplary transition between a CELL_DCHconnected mode state and an idle mode initiated by the UTRAN accordingto current method;

FIG. 4B is a block diagram showing an exemplary transition between aCELL_DCH state connected mode transition to an idle mode according tothe present method and apparatus;

FIG. 5A is a block diagram of an exemplary transition between a CELL_DCHinactivity to a CELL_FACH inactivity to an idle mode initiated by theUTRAN according to current method;

FIG. 5B is a block diagram of an exemplary transition between CELL_DCHinactivity and an idle mode according to the present method;

FIG. 6 is a block diagram of a UMTS protocol stack;

FIG. 7 is an exemplary UE that can be used in association with thepresent method; and

FIG. 8 is an exemplary network for use in association with the presentmethod and apparatus.

DETAILED DESCRIPTION

The present system and method overcome certain deficiencies of the priorart by providing the transitioning from an RRC connected mode to a morebattery efficient state or mode. In particular, the present method andapparatus preferably provide for transitioning based on either the UEinitiating termination of a signaling connection for a specified corenetwork domain or indicating to the UTRAN that a transition should occurfrom one connected state to another.

In particular, if an application on the UE determines that it is donewith the exchange of data, it can send a “done” indication to the “RRCconnection manager” component of UE software. The RRC connection managerkeeps track of all existing applications (including those providing aservice over one or multiple protocols), associated Packet Data Protocol(PDP) contexts, associated packet switched (PS) radio bearers andassociated circuit switched (CS) radio bearers. A PDP Context is alogical association between a UE and PDN (Public Data Network) runningacross a UMTS core network. One or multiple applications (e.g. an e-mailapplication and a browser application) on the UE may be associated withone PDP context. In some cases, one application on the UE is associatedwith one primary PDP context and multiple applications may be tied withsecondary PDP contexts. The RRC Connection Manager receives “done”indications from different applications on the UE that aresimultaneously active. For example, user may receive an e-mail from apush server while browsing the web. After the e-mail application hassent an acknowledgment, it may indicate that it has completed its datatransaction, however, the browser application may not send suchindication. Based on a composite status of such indications from activeapplications, UE software can decide how long it should wait before itcan initiate a signaling connection release of the core network packetservice domain. A delay in this case can be introduced to ensure thatthe application is truly finished with data exchange and does notrequire an RRC connection. The delay can be dynamic based on traffichistory and/or application profiles. Whenever the RRC connection managerdetermines that with some probability that no application is expected toexchange any data, it can send a signaling connection release indicationprocedure for the appropriate domain (e.g. PS domain). Alternatively itcan send a request for state transition within connected mode to theUTRAN.

The above decision may also take into account whether network supportsURA_PCH state and the transition behaviour to this state.

The UE initiated transition to idle mode can happen from any state ofthe RRC connected mode and ends up having the network release the RRCconnection and moving to idle mode. The UE being in idle mode, as willbe appreciated by those skilled in the art, is much less batteryintensive than the UE being in a connected state.

The present application therefore preferable provides a method forimproved battery performance of user equipment in a wireless networkhaving multiple radio resource control (RRC) states, comprising thesteps of: monitoring, at the user equipment, application data exchange;determining when no application on the user equipment is expected toexchange data; and initiating, from the user equipment, a transition toa less battery demanding radio resource control state or mode.

The present application further preferably provides user equipmentadapted for reduces battery consumption in a UMTS network, the userequipment having a radio subsystem including a radio adapted tocommunicate with the UMTS network; a radio processor having a digitalsignal processor and adapted to interact with said radio subsystem;memory; a user interface; a processor adapted to run user applicationsand interact with the memory, the radio and the user interface andadapted to run applications, the user equipment characterized by havingmeans for; monitoring, at the user equipment, application data exchange;determining when no application on the user equipment is expected toexchange date; and initiating, from the user equipment, a transition toa less battery demanding radio resource control state or mode.

Reference is now made to FIG. 1. FIG. 1 is a block diagram showing thevarious modes and states for the radio resource control portion of aprotocol stack in a UMTS network. In particular, the RRC can be eitherin an RRC idle state 110 or an RRC connected state 120.

As will be appreciated by those skilled in the art, a UMTS networkconsists of two land-based network segments. These are the Core Network(CN) and the Universal Terrestrial Radio-Access Network (UTRAN) (asillustrated in FIG. 8). The Core Network is responsible for theswitching and routing of data calls and data connections to the externalnetworks while the UTRAN handles all radio related functionalities.

In idle mode 110, the UE must request an RRC connection to set up theradio resource whenever data needs to be exchanged between the UE andthe network. This can be as a result of either an application on the UErequiring a connection to send data, or as a result of the UE monitoringa paging channel to indicate whether the UTRAN or SGSN has paged the UEto receive data from an external data network such as a push server. Inaddition, UE also requests RRC connection whenever it needs to sendMobility Management signaling message such as Location Area Update.

Once the UE has sent a request to the UTRAN to establish a radioconnection, the UTRAN chooses a state for the RRC connection to be in.Specifically, the RRC connected mode 120 includes four separate states.These are CELL_DCH state 122, CELL_FACH state 124, CELL_PCH state 126and URA_PCH state 128.

From idle mode 110 the RRC connected state can either go to the CellDedicated Channel (CELL_DCH) state 122 or the Cell Forward AccessChannel (CELL_FACH) state 124.

In CELL_DCH state 122, a dedicated channel is allocated to the UE forboth uplink and downlink to exchange data. This state, since it has adedicated physical channel allocated to the UE, typically requires themost battery power from the UE.

Alternatively, the UTRAN can move from idle mode 110 to a CELL_FACHstate 124. In a CELL_FACH state no dedicated channel is allocated to theUE. Instead, common channels are used to send signaling in a smallamount of bursty data. However, the UE still has to continuously monitorthe FACH, and therefore it consumes battery power.

Within the RRC connected mode 120, the RRC state can be changed at thediscretion of the UTRAN. Specifically, if data inactivity is detectedfor a specific amount of time or data throughput below a certainthreshold is detected, the UTRAN may move the RRC state from CELL_DCHstate 122 to the CELL_FACH state 124, CELL_PCH state 126 or URA_PCHstate 128. Similarly, if the payload is detected to be above a certainthreshold then the RRC state can be moved from CELL_FACH 124 to CELL_DCH122.

From CELL_FACH state 124, if data inactivity is detected forpredetermined time in some networks, the UTRAN can move the RRC statefrom CELL_FACH state 124 to a paging channel (PCH) state. This can beeither the CELL_PCH state 126 or URA_PCH state 128.

From CELL_PCH state 126 or URA_PCH state 128 the UE must move toCELL_FACH state 124 in order to initiate an update procedure to requesta dedicated channel. This is the only state transition that the UEcontrols.

CELL_PCH state 126 and URA_PCH state 128 use a discontinuous receptioncycle (DRX) to monitor broadcast messages and pages by a PagingIndicator Channel (PICH). No uplink activity is possible.

The difference between CELL_PCH state 126 and URA_PCH state 128 is thatthe URA_PCH state only triggers a URA Update procedure if the UEscurrent UTRAN registration area (URA) is not among the list of URAidentities present in the current cell. Specifically, reference is madeto FIG. 2. FIG. 2 shows an illustration of various UMTS cells 210, 212and 214. All of these cells require a cell update procedure ifreselected to a CELL_PCH state. However, in a UTRAN registration area,each will be within the same UTRAN registration area 220, and thus a URAupdate procedure is not triggered when moving between 210, 212 and 214when in a URA_PCH mode.

As seen in FIG. 2, other cells 218 are outside the URA 220, and can bepart of a separate URA or no URA.

As will be appreciated by those skilled in the art, from a battery lifeperspective the idle state provides the lowest battery usage comparedwith the states above. Specifically, because the UE is required tomonitor the paging channel only at intervals, the radio does not need tocontinuously be on, but will instead wake up periodically. The trade-offfor this is the latency to send data. However, if this latency is nottoo great, the advantages of being in the idle mode and saving batterypower outweigh the disadvantages of the connection latency.

Reference is again made to FIG. 1. Various UMTS infrastructure vendorsmove between states 122, 124, 126 and 128 based on various criteria.Exemplary infrastructures are outlined below.

In a first exemplary infrastructure, the RRC moves between an idle modeand a Cell_DCH state directly. In the Cell_DCH state, if two seconds ofinactivity are detected, the RRC state changes to a Cell_FACH state 124.If in Cell_FACH state 124, ten seconds of inactivity are detected thenthe RRC state changes to PCH state 126. Forty five minutes of inactivityin Cell_PCH states 126 will result in the RRC state moving back to idlemode 110.

In a second exemplary infrastructure, RRC transition can occur betweenan idle mode 110 and connected mode 120 depending on a payloadthreshold. In the second infrastructure, if the payload is below acertain threshold then the UTRAN moves the RRC state to CELL_FACH state124. Conversely, if the data is above a certain payload threshold thenthe UTRAN moves the RRC state a CELL_DCH state 122. In the secondinfrastructure, if two minutes of inactivity are detected in CELL_DCHstate 122, the UTRAN moves the RRC state to CELL_FACH state 124. Afterfive minutes of inactivity in the CELL-FACH state 124, the UTRAN movesthe RRC stage to CELL_PCH state 126. In CELL_PCH state 126, two hours ofinactivity are required before moving back to idle mode 110.

In a third exemplary infrastructure, movement between idle mode andconnected mode 120 is always to CELL_DCH state 122. After five secondsof inactivity in CELL_DCH state 122 the UTRAN moves the RRC state toCELL_FACH state 124. Thirty seconds of inactivity in CELL_FACH state 124results in the movement back to idle mode 110.

In a fourth exemplary infrastructure the RRC transitions from an idlemode to a connected mode directly into a CELL_DCH state 122. In thefourth exemplary infrastructure, CELL_DCH state 122 includes twosub-states. The first includes a sub-state which has a high data rateand a second sub-state includes a lower data rate, but still within theCELL_DCH state. In the fourth exemplary infrastructure, the RRCtransitions from idle mode 110 directly into the high data rate CELL_DCHsub-state. After 10 seconds of inactivity the RRC state transitions to alow data rate CELL_DCH state. Seventeen seconds of inactivity from thelow data CELL_DCH state 122 result in the RRC state changing it to idlemode 110.

The above four exemplary infrastructure shows how various UMTSinfrastructure vendors are implementing the states. As will beappreciated by those skilled in the art, in each case, if the time spenton exchanging actual data (such as an email) is significantly shortcompared to the time that is required to stay in the CELL_DCH or theCELL_FACH states, this causes unnecessary current drain which makes userexperience in newer generation networks such as UMTS worse than in priorgeneration networks such as GPRS.

Further, although the CELL_PCH state is more optimal than the CELL_FACHstate from a battery life perspective, the DRX cycle in a CELL_PCH stateis typically set to a lower value than the idle mode 110. As a result,the UE is required to wake up more frequently in the CELL_PCH state thanin an idle mode.

The URA_PCH state with a DRX cycle similar to that of the idle state islikely the optimal trade up between battery life and latency forconnection. However, URA_PCH is currently not supported in the UTRAN. Itis therefore desirable to quickly transition to the idle mode as quicklyas possible after an application is finished with the data exchange froma battery life perspective.

Reference is now made to FIG. 3. When transitioning from an idle mode toa connected mode various signaling and data connections need to be made.Referring to FIG. 3, the first item needing to be performed is an RRCconnection set-up. As indicated above, this RRC connection setup canonly be torn down by the UTRAN.

Once RRC connection setup 310 is accomplished, a signaling connectionsetup 312 is started.

Once signaling setup 312 is finished, a ciphering and integrity setup314 is started. Upon completion of this, a radio bearer setup 316 isaccomplished. At this point, data can be exchanged between the UE andUTRAN.

Tearing down a connection is similarly accomplished in the reverseorder, in general. The radio bearer setup 316 is taken down and then theRRC connection setup 310 is taken down. At this point, the RRC movesinto idle mode 110 as illustrated in FIG. 1.

Although the current 3GPP specification does not allow the UE to releasethe RRC connection or indicate its preference for RRC state, the UE canstill indicate termination of a signaling connection for a specifiedcore network domain such as the Packet Switched (PS) domain used bypacket-switched applications. According to section 8.1.14.1 of 3GPP TS25.331;

-   -   The signaling connection release indication procedure is used by        the UE to indicate to the UTRAN that one of its signaling        connection has been released. This procedure may in turn        initiate the RRC connection release procedure.

Thus staying within the current 3GPP specifications, signalingconnection release may be initiated upon the tearing down of thesignaling connection setup 312. It is within the ability of the UE totear down signaling connection setup 312, and this in turn according tothe specification “may” initiate the RRC connection release.

As will be appreciated by those skilled in the art, if signalingconnection setup 312 is torn down, the UTRAN will also need to clean updeciphering and integrity setup 312 radio bearer setup 316 after thesignaling connection setup 312 has been torn down.

If signaling connections setup 312 is torn down, the RRC connectionsetup is typically brought down by the network for current vendorinfrastructures.

Using the above, if the UE determines that it is done with the exchangeof data, for example if a “RRC connection manager” component of the UEsoftware is provided with an indication that the exchange of data iscomplete, then the RRC connection manager may determine whether or notto tear down the signaling connection setup 312. For example, an emailapplication on the device sends an indication that it has received anacknowledgement from the push email server that the email was indeedreceived by the push server. The RRC manager can keep track of allexisting applications, associated PDP contexts, associated PS radiobearers and associated circuit switched (CS) radio bearers. A delay inthis case can be introduced to ensure that the application is trulyfinished with data exchange and no longer requires an RRC connectioneven after it has sent the “done” indication. This delay is equivalentto inactivity timeout associated with the application. Each applicationcan have its own inactivity timeout. For example, an email applicationcan have an inactivity timeout of five seconds, whereas an activebrowser application can have a timeout of sixty seconds. Based on acomposite status of all such indications from active applications, theUE software decides how long it should wait before it can initiate asignaling connection release of the appropriate core network (e.g. PSDomain).

The inactivity timeout can be made dynamic based on a traffic patternhistory and/or application profile.

Whenever the RRC connection manager determines with some probabilitythat no application is expected the exchange of data, it can send asignaling connection release indication procedure for the appropriatedomain.

The above UE initiated transition to idle mode can happen in any stageof the RRC connected mode 120 as illustrated in FIG. 1 and ends uphaving the network release the RRC connection and moving to a idle mode110 as illustrated in FIG. 1. This is also applicable when the UE isperforming any packet data services during a voice call. In this caseonly the PS domain is released, but the CS domain remains connected.

As will be appreciated by those skilled in the art, in some cases it maybe more desirable to be in the connected mode state URA_PCH than in idlemode. For example, if the latency for connection to the CELL_DCH or theCELL_FACH connected mode states is required to be lower, it ispreferable to be in a connected mode PCH state. There are two ways ofaccomplishing this. First is by changing the 3GPP specifications toallow for the UE to request the UTRAN move it to a specific state, inthis case the URA_PCH state 128.

Alternatively, the RRC connection manager may take into account otherfactors such as what state the RRC connection is currently in. If, forexample, the RRC connection is in the URA_PCH state it may decide thatit is unnecessary to move to idle mode 110 and thus no Signalingconnection release procedure is initiated.

Reference is made to FIG. 4. FIG. 4A shows a current UMTS implementationaccording to the infrastructure “four” example above. As illustrated inFIG. 4, time is across the horizontal axes.

The UE starts in RRC idle state 110 and based on local data needing tobe transmitted or a page received from the UTRAN, starts to establish anRRC connection.

As illustrated in FIG. 4A, RRC connection setup 310 occurs first, andthe RRC state is a connecting state 410 during this time.

Next, signaling connections setup 312, ciphering an integrity setup 314,and radio bearer setup 316 occurs. The RRC state is CELL_DCH state 122during this. As illustrated in FIG. 4A, the time for moving from RRCidle to the time that the radio bearer is setup is approximately twoseconds in this example.

Data is next exchanged. In the example FIG. 4A this is achieved in abouttwo to four seconds and is illustrated by step 420.

After data is exchanged in step 420, no data is being exchanged exceptfor intermittent RLC signaling PDU as required and thus the radio beareris reconfigured by the network to move into a lower data rate DCH stateafter approximately ten seconds. This is illustrated in steps 422 and424.

In the lower data rate DCH state nothing is received for seventeenseconds, at which point the RRC connection is released by the network instep 428.

Once the RRC connection is initiated in step 428, the RRC state proceedsto a disconnecting state 430 for approximately forty milliseconds, afterwhich the UE is in a RRC idle state 110.

Also illustrated in FIG. 4A, the UE current consumption is illustratedfor the period in which the RRC is in CELL_DCH state 122. As seen, thecurrent consumption is approximately 200 to 300 milliamps for the entireduration of the CELL_DCH state. During disconnect and idle, about 3milliamps are utilized, assuming a DRX cycle of 1.28 seconds. However,the 35 seconds of current consumption at 200 to 300 milliamps isdraining on the battery.

Reference is now made to FIG. 4B. FIG. 4B utilizes the same exemplaryinfrastructure “four” from above, only now implementing the signallingconnection release.

As illustrated in FIG. 4B, the same setup steps 310, 312, 314 and 316occur and this takes the same amount of time when moving between RRCidle state 110 and RRC CELL_DCH state 122.

Further, the RRC data PDU exchange for the exemplary email of FIG. 4A isalso done at FIG. 4B and this takes approximately two to four seconds.

The UE in the example of FIG. 4B has an application specific inactivitytimeout, which in the example of FIG. 4B is two seconds and isillustrated by step 440. After the RRC connection manager has determinedthat there is inactivity for the specific amount of time, the UEreleases the signaling connection setup in step 442 and the RRCconnection is released by the network in step 428.

As illustrated in FIG. 4B, the current consumption during the CELL_DCHstep 122 is still about 200 to 300 milliamps. However, the connectiontime is only about eight seconds. As will appreciated by those skilledin the art, the considerably shorter amount of time that the mobilestays in the cell DCH state 122 results in significant battery savingsfor an always on UE device.

Reference is now made to FIG. 5. FIG. 5 shows a second example using theinfrastructure indicated above as Infrastructure “three”. As with FIGS.4A and 4B, a connection setup occurs which takes approximately twoseconds. This requires the RRC connection setup 310, the signalingconnection setup 312, the ciphering and integrity setup 314 and theradio bearer setup 316.

During this setup, the UE moves from RRC idle mode 110 to a CELL_DCHstate 122 with a RRC state connecting step 410 in between.

As with FIG. 4A, in FIG. 5A RLC data PDU exchange occurs, and in theexample of FIG. 5A takes two to four seconds.

According to the infrastructure three, RLC signaling PDU exchangereceives no data and thus is idle for period of five seconds in step422, except for intermittent RLC signaling PDU as required, at whichpoint the radio bearer reconfigures the network to move into a CELL_FACHstate 124 from CELL_DCH state 122. This is done in step 450.

In the CELL_FACH state 124, the RLC signaling PDU exchange finds thatthere is no data except for intermittent RLC signaling PDU as requiredfor a predetermined amount of time, in this case thirty seconds, atwhich point a RRC connection release by network is performed in step428.

As seen in FIG. 5A, this moves the RRC state to idle mode 110.

As further seen in FIG. 5A, the current consumption during the DCH modeis between 200 and 300 milliamps. When moving into CELL_FACH state 124the current consumption lowers to approximately 120 to 180 milliamps.After the RRC connector is released and the RRC moves into idle mode 110the power consumption is approximately 3 milliamps.

The UTRA RRC Connected Mode state being CELL_DCH state 122 or CELL_FACHstate 124 lasts for approximately forty seconds in the example of FIG.5A.

Reference is now made to FIG. 5B. FIG. 5B illustrates the sameinfrastructure “three” as FIG. 5A with the same connection time of abouttwo seconds to get the RRC connection setup 310, signaling connectionsetup 312, ciphering integrity setup 314 and radio bearer setup 316.Further, RLC data PDU exchange 420 take approximately two to fourseconds.

As with FIG. 4B, a UE application detects a specific inactivity timeoutin step 440, at which point the Signalling connection release indicationprocedure is initiated by the UE and as a consequence the RRC connectionis released by the network in step 448.

As can be seen further in FIG. 5B, the RRC starts in a idle mode 110,moves to a CELL_DCH state 122 without proceeding into the CELL_FACHstate.

As will be seen further in FIG. 5B, current consumption is approximately200 to 300 milliamps in the time that the RRC stage is in CELL_DCH state122 which according to the example of FIG. 5 is approximate eightseconds.

Therefore, a comparison between FIGS. 4A and 4B, and FIGS. 5A and 5Bshows that a significant amount of current consumption is eliminated,thereby extending the battery life of the UE significantly. As will beappreciated by those skilled in the art, the above can further be usedin the context of current 3GPP specs.

Reference is now made to FIG. 6. FIG. 6 illustrates a protocol stack fora UMTS network.

As seen in FIG. 6, the UMTS includes a CS control plane 610, PS controlplane 611, and PS user plane 630

Within these three planes, a non-access stratum (NAS) portion 614 and anaccess stratum portion 616 exist.

NAS portion 614 in CS control plane 610 includes a call control (CC)618, supplementary services (SS) 620, and short message service (SMS)622.

NAS portion 614 in PS control plane 611 includes both mobilitymanagement (MM) and GPRS mobility management (GMM) 626. It furtherincludes SM/RABM 624 and GSMS 628.

CC 618 provides for call management signaling for circuit switchedservices. The session management portion of SM/RABM 624 provides for PDPcontext activation, deactivation and modification. SM/RABM 624 alsoprovides for quality of service negotiation.

The main function of the RABM portion of the SM/RABM 624 is to connect aPDP context to a Radio Access Bearer. Thus SM/RABM 624 is responsiblefor the setup, modification and release of radio bearers.

CS control plane 610 and PS control plane 611, in the access stratum 616sit on radio resource control (RRC) 617.

NAS portion 614 in PS user plane 630 includes an application layer 638,TCP/UDP layer 636, and PDP layer 634. PDP layer 634 can, for example,include internet protocol (IP).

Access Stratum 616, in PS user plane 630 includes packet dataconvergence protocol (PDCP) 632. PDCP 632 is designed to make the WCDMAprotocol suitable to carry TCP/IP protocol between UE and RNC (as seenin FIG. 8), and is optionally for IP traffic stream protocol headercompression and decompression.

The UMTS Radio Link Control (RLC) 640 and Medium Access Control (MAC)layers 650 form the data link sub-layers of the UMTS radio interface andreside on the RNC node and the User Equipment.

The Layer 1 (L1) UMTS layer (physical layer 650) is below the RLC/MAClayers 640 and 650. This layer is the physical layer for communications.

While the above can be implemented on a variety of mobile devices, anexample of one mobile device is outlined below with respect to FIG. 7.Reference is now made to FIG. 7.

UE 1100 is preferably a two-way wireless communication device having atleast voice and data communication capabilities. UE 1100 preferably hasthe capability to communicate with other computer systems on theInternet. Depending on the exact functionality provided, the wirelessdevice may be referred to as a data messaging device, a two-way pager, awireless e-mail device, a cellular telephone with data messagingcapabilities, a wireless Internet appliance, or a data communicationdevice, as examples.

Where UE 1100 is enabled for two-way communication, it will incorporatea communication subsystem 1111, including both a receiver 1112 and atransmitter 1114, as well as associated components such as one or more,preferably embedded or internal, antenna elements 1116 and 1118, localoscillators (LOs) 1113, and a processing module such as a digital signalprocessor (DSP) 1120. As will be apparent to those skilled in the fieldof communications, the particular design of the communication subsystem1111 will be dependent upon the communication network in which thedevice is intended to operate. For example, UE 1100 may include acommunication subsystem 1111 designed to operate within the GPRS networkor UMTS network.

Network access requirements will also vary depending upon the type ofnetwork 1119. For example, In UMTS and GPRS networks, network access isassociated with a subscriber or user of UE 1100. For example, a GPRSmobile device therefore requires a subscriber identity module (SIM) cardin order to operate on a GPRS network. In UMTS a USIM or SIM module isrequired. In CDMA a RUIM card or module is required. These will bereferred to as a UIM interface herein. Without a valid UIM interface, amobile device may not be fully functional. Local or non-networkcommunication functions, as well as legally required functions (if any)such as emergency calling, may be available, but mobile device 1100 willbe unable to carry out any other functions involving communications overthe network 1100. The UIM interface 1144 is normally similar to acard-slot into which a card can be inserted and ejected like a disketteor PCMCIA card. The UIM card can have approximately 64K of memory andhold many key configuration 1151, and other information 1153 such asidentification, and subscriber related information.

When required network registration or activation procedures have beencompleted, UE 1100 may send and receive communication signals over thenetwork 1119. Signals received by antenna 1116 through communicationnetwork 1119 are input to receiver 1112, which may perform such commonreceiver functions as signal amplification, frequency down conversion,filtering, channel selection and the like, and in the example systemshown in FIG. 7, analog to digital (ND) conversion. ND conversion of areceived signal allows more complex communication functions such asdemodulation and decoding to be performed in the DSP 1120. In a similarmanner, signals to be transmitted are processed, including modulationand encoding for example, by DSP 1120 and input to transmitter 1114 fordigital to analog conversion, frequency up conversion, filtering,amplification and transmission over the communication network 1119 viaantenna 1118. DSP 1120 not only processes communication signals, butalso provides for receiver and transmitter control. For example, thegains applied to communication signals in receiver 1112 and transmitter1114 may be adaptively controlled through automatic gain controlalgorithms implemented in DSP 1120.

Network 1119 may further communicate with multiple systems, including aserver 1160 and other elements (not shown). For example, network 1119may communicate with both an enterprise system and a web client systemin order to accommodate various clients with various service levels.

UE 1100 preferably includes a microprocessor 1138 which controls theoverall operation of the device. Communication functions, including atleast data communications, are performed through communication subsystem1111. Microprocessor 1138 also interacts with further device subsystemssuch as the display 1122, flash memory 1124, random access memory (RAM)1126, auxiliary input/output (I/O) subsystems 1128, serial port 1130,keyboard 1132, speaker 1134, microphone 1136, a short-rangecommunications subsystem 1140 and any other device subsystems generallydesignated as 1142.

Some of the subsystems shown in FIG. 7 perform communication-relatedfunctions, whereas other subsystems may provide “resident” or on-devicefunctions. Notably, some subsystems, such as keyboard 1132 and display1122, for example, may be used for both communication-related functions,such as entering a text message for transmission over a communicationnetwork, and device-resident functions such as a calculator or tasklist.

Operating system software used by the microprocessor 1138 is preferablystored in a persistent store such as flash memory 1124, which mayinstead be a read-only memory (ROM) or similar storage element (notshown). Those skilled in the art will appreciate that the operatingsystem, specific device applications, or parts thereof, may betemporarily loaded into a volatile memory such as RAM 1126. Receivedcommunication signals may also be stored in RAM 1126. Further, a uniqueidentifier is also preferably stored in read-only memory.

As shown, flash memory 1124 can be segregated into different areas forboth computer programs 1158 and program data storage 1150, 1152, 1154and 1156. These different storage types indicate that each program canallocate a portion of flash memory 1124 for their own data storagerequirements. Microprocessor 1138, in addition to its operating systemfunctions, preferably enables execution of software applications on themobile device. A predetermined set of applications that control basicoperations, including at least data and voice communication applicationsfor example, will normally be installed on UE 1100 during manufacturing.A preferred software application may be a personal information manager(PIM) application having the ability to organize and manage data itemsrelating to the user of the mobile device such as, but not limited to,e-mail, calendar events, voice mails, appointments, and task items.Naturally, one or more memory stores would be available on the mobiledevice to facilitate storage of PIM data items. Such PIM applicationwould preferably have the ability to send and receive data items, viathe wireless network 1119. In a preferred embodiment, the PIM data itemsare seamlessly integrated, synchronized and updated, via the wirelessnetwork 1119, with the mobile device user's corresponding data itemsstored or associated with a host computer system. Further applicationsmay also be loaded onto the mobile device 1100 through the network 1119,an auxiliary I/O subsystem 1128, serial port 1130, short-rangecommunications subsystem 1140 or any other suitable subsystem 1142, andinstalled by a user in the RAM 1126 or preferably a non-volatile store(not shown) for execution by the microprocessor 1138. Such flexibilityin application installation increases the functionality of the deviceand may provide enhanced on-device functions, communication-relatedfunctions, or both. For example, secure communication applications mayenable electronic commerce functions and other such financialtransactions to be performed using the UE 1100. These applications willhowever, according to the above, in many cases need to be approved by acarrier.

In a data communication mode, a received signal such as a text messageor web page download will be processed by the communication subsystem1111 and input to the microprocessor 1138, which preferably furtherprocesses the received signal for output to the display 1122, oralternatively to an auxiliary I/O device 1128. A user of UE 1100 mayalso compose data items such as email messages for example, using thekeyboard 1132, which is preferably a complete alphanumeric keyboard ortelephone-type keypad, in conjunction with the display 1122 and possiblyan auxiliary I/O device 1128. Such composed items may then betransmitted over a communication network through the communicationsubsystem 1111.

For voice communications, overall operation of UE 1100 is similar,except that received signals would preferably be output to a speaker1134 and signals for transmission would be generated by a microphone1136. Alternative voice or audio I/O subsystems, such as a voice messagerecording subsystem, may also be implemented on UE 1100. Although voiceor audio signal output is preferably accomplished primarily through thespeaker 1134, display 1122 may also be used to provide an indication ofthe identity of a calling party, the duration of a voice call, or othervoice call related information for example.

Serial port 1130 in FIG. 7 would normally be implemented in a personaldigital assistant (PDA)-type mobile device for which synchronizationwith a user's desktop computer (not shown) may be desirable. Such a port1130 would enable a user to set preferences through an external deviceor software application and would extend the capabilities of mobiledevice 1100 by providing for information or software downloads to UE1100 other than through a wireless communication network. The alternatedownload path may for example be used to load an encryption key onto thedevice through a direct and thus reliable and trusted connection tothereby enable secure device communication.

Alternatively, serial port 1130 could be used for other communications,and could include as a universal serial bus (USB) port. An interface isassociated with serial port 1130.

Other communications subsystems 1140, such as a short-rangecommunications subsystem, is a further optional component which mayprovide for communication between UE 1100 and different systems ordevices, which need not necessarily be similar devices. For example, thesubsystem 1140 may include an infrared device and associated circuitsand components or a Bluetooth™ communication module to provide forcommunication with similarly enabled systems and devices.

Reference is now made to FIG. 8. FIG. 8 is a block diagram of acommunication system 800 which includes a UE 802 which communicatesthrough a wireless communication network.

UE 802 communicates wirelessly with one of multiple Node Bs 806. EachNode B 806 is responsible for air interface processing and some radioresource management functions. Node B 806 provides functionality similarto a Base Transceiver Station in a GSM/GPRS networks.

The wireless link shown in communication system 800 of FIG. 8 representsone or more different channels, typically different radio frequency (RF)channels, and associated protocols used between the wireless network andUE 802. A Uu air interface 804 is used between UE 802 and Node B 806.

An RF channel is a limited resource that must be conserved, typicallydue to limits in overall bandwidth and a limited battery power of UE802. Those skilled in art will appreciate that a wireless network inactual practice may include hundreds of cells depending upon desiredoverall expanse of network coverage. All pertinent components may beconnected by multiple switches and routers (not shown), controlled bymultiple network controllers.

Each Node B 806 communicates with a radio network controller (RNC) 810.The RNC 810 is responsible for control of the radio resources in itsarea. One RNC 810 control multiple Node Bs 806.

The RNC 810 in UMTS networks provides functions equivalent to the BaseStation Controller (BSC) functions in GSM/GPRS networks. However, an RNC810 includes more intelligence including, for example, autonomoushandovers management without involving MSCs and SGSNs.

The interface used between Node B 806 and RNC 810 is an Iub interface808. An NBAP (Node B application part) signaling protocol is primarilyused, as defined in 3GPP TS 25.433 V3.11.0 (2002-09) and 3GPP TS 25.433V5.7.0 (2004-01).

Universal Terrestrial Radio Access Network (UTRAN) 820 comprises the RNC810, Node B 806 and the Uu air interface 804.

Circuit switched traffic is routed to Mobile Switching Centre (MSC) 830.MSC 830 is the computer that places the calls, and takes and receivesdata from the subscriber or from PSTN (not shown).

Traffic between RNC 810 and MSC 830 uses the Iu-CS interface 828. Iu-CSinterface 828 is the circuit-switched connection for carrying(typically) voice traffic and signaling between UTRAN 820 and the corevoice network. The main signaling protocol used is RANAP (Radio AccessNetwork Application Part). The RANAP protocol is used in UMTS signalingbetween the Core Network 821, which can be a MSC 830 or SSGN 850(defined in more detail below) and UTRAN 820. RANAP protocol is definedin 3GPP TS 25.413 V3.11.1 (2002-09) and TS 25.413 V5.7.0 (2004-01).

For all UEs 802 registered with a network operator, permanent data (suchas UE 102 user's profile) as well as temporary data (such as UE's 802current location) are stored in a home location registry (HLR) 838. Incase of a voice call to UE 802, HLR 838 is queried to determine thecurrent location of UE 802. A Visitor Location Register (VLR) 836 of MSC830 is responsible for a group of location areas and stores the data ofthose mobile stations that are currently in its area of responsibility.This includes parts of the permanent mobile station data that have beentransmitted from HLR 838 to the VLR 836 for faster access. However, theVLR 836 of MSC 830 may also assign and store local data, such astemporary identifications. UE 802 is also authenticated on system accessby HLR 838.

Packet data is routed through Service GPRS Support Node (SGSN) 850. SGSN850 is the gateway between the RNC and the core network in a GPRS/UMTSnetwork and is responsible for the delivery of data packets from and tothe UEs within its geographical service area. Iu-PS interface 848 isused between the RNC 810 and SGSN 850, and is the packet-switchedconnection for carrying (typically) data traffic and signaling betweenthe UTRAN 820 and the core data network. The main signaling protocolused is RANAP (described above).

The SSGN 850 communicates with the Gateway GPRS Support Node (GGSN) 860.GGSN 860 is the interface between the UMTS/GPRS network and othernetworks such as the Internet or private networks. GGSN 860 is connectedto a public data network PDN 870 over a Gi interface.

Those skilled in art will appreciate that wireless network may beconnected to other systems, possibly including other networks, notexplicitly shown in FIG. 8. A network will normally be transmitting atvery least some sort of paging and system information on an ongoingbasis, even if there is no actual packet data exchanged. Although thenetwork consists of many parts, these parts all work together to resultin certain behaviours at the wireless link.

The embodiments described herein are examples of structures, systems ormethods having elements corresponding to elements of the techniques ofthis application. This written description may enable those skilled inthe art to make and use embodiments having alternative elements thatlikewise correspond to the elements of the techniques of thisapplication. The intended scope of the techniques of this applicationthus includes other structures, systems or methods that do not differfrom the techniques of this application as described herein, and furtherincludes other structures, systems or methods with insubstantialdifferences from the techniques of this application as described herein.

1. A method of transitioning a user equipment between radio resourcecontrol (RRC) states or modes in a wireless network, the methodcomprising at the user equipment: determining that no further dataexchange is expected; and when no further data is expected, sending amessage to the wireless network for a network controlled transition froma first RRC state or mode to a second RRC state or mode that is a lessbattery demanding RRC state or mode than the first RRC state or mode. 2.A method according to claim 1, wherein the message comprises a signalingconnection release indication (SCRI) message.
 3. A method according toclaim 1, wherein the wireless network comprises a Universal TerrestrialRadio Access Network (UTRAN).
 4. A method according to claim 1, whereinthe wireless network comprises a Universal Mobile TelecommunicationsSystem (UMTS) network.
 5. A method according to claim 3, wherein thefirst RRC state or mode is one of a CELL_DCH state and a CELL_FACHstate.
 6. A method according to claim 3, wherein the first RRC state ormode is one of a CELL_PCH state and a URA_PCH state.
 7. A methodaccording to claim 1, wherein the second RRC state or mode is one of aCELL_FACH state, a CELL_PCH state, a URA_PCH state and an idle mode. 8.A method according to claim 1, further comprising at the user equipmentreleasing a signaling connection set-up between the user equipment andthe network.
 9. A method according to claim 1, wherein the message is arequest for release of a signaling connection for a core network domain.10. A method according to claim 9, wherein the core network domain is apacket switched domain.
 11. A method according to claim 8, wherein therelease of the signaling connection set-up by the user equipment causesthe wireless network to release a signaling connection between the userequipment and the network.
 12. A method according to claim 1, whereinthe step of determining that no further data exchange is expectedcomprises a determination that no application at the user equipment isexpected to exchange data.
 13. A method according to claim 1, whereinthe determination that no further data exchange is expected is based ona composite status of data exchange completion indications received fromany application that exchanged data in the first RRC state or mode. 14.A method according to claim 1, wherein sending a message to the wirelessnetwork for a network controlled transition is only performed if thefirst RRC state or mode is not a URA_PCH state.
 15. A user equipment foruse in a wireless network, the user equipment comprising an RRCconnection manager adapted to determine when no further data exchange isexpected; and when no further data is expected, to send a message to thenetwork for a network controlled transition from a first RRC state ormode to a second RRC state or mode that is a less battery demanding RRCstate or mode than the first RRC state or mode.
 16. The user equipmentaccording to claim 15, wherein the message comprises a signalingconnection release indication (SCRI) message.
 17. The user equipmentaccording to claim 15, wherein the wireless network comprises aUniversal Terrestrial Radio Access Network (UTRAN).
 18. The userequipment according to claim 15, wherein the wireless network comprisesa Universal Mobile Telecommunications System (UMTS) network.
 19. Theuser equipment according to claim 17, wherein the first RRC state ormode is one of a CELL_DCH state and a CELL_FACH state.
 20. The userequipment according to claim 17, wherein the first RRC state or mode isone of a CELL_PCH state and a URA_PCH state.
 21. The user equipmentaccording to claim 15, wherein the second RRC state or mode is one of aCELL_FACH state, a CELL_PCH state, a URA_PCH state and an idle mode. 22.The user equipment according to claim 15, wherein the RRC connectionmanager is further adapted to release a signaling connection set-upbetween the user equipment and the network.
 23. The user equipmentaccording to claim 15, wherein the message is a request for release of asignaling connection for a core network domain.
 24. The user equipmentaccording to claim 23, wherein the core network domain is a packetswitched domain.
 25. The user equipment according to claim 22, whereinthe release of the signaling connection set-up by the user equipment iffor causing the wireless network to release a signaling connectionbetween the user equipment and the network.
 26. The user equipmentaccording to claim 15, wherein the RRC connection manager is adapted todetermine that no further data exchange is expected by determining thatno application at the user equipment is expected to exchange data. 27.The user equipment according to claim 15, wherein the determination thatno further data exchange is expected is based on a composite status ofdata exchange completion indications received from any application ofthe user equipment that exchanged data in the first RRC state or mode.28. The user equipment according to claim 15, wherein the RRC connectionmanager is further adapted to send a message to the wireless network fora network controlled transition only if the first RRC state or mode isnot a URA_PCH state.